Use of linear injectors to deposit uniform selective ozone teos oxide film by pulsing reactants on and off

ABSTRACT

A process for enhanced selective deposition of a silicon oxide onto a substrate by pulsing delivery of the reactants through a linear injector is disclosed. The silicon oxide layer is formed by the ozone decomposition of TEOS at relatively low temperatures and relatively high pressures. The ozone delivery is pulsed on and off. Optionally, the delivery of the ozone and the delivery of the TEOS are pulsed on and off alternately.

[0001] This is a continuation-in-part of U.S. patent application Ser.No. 09/652,188 filed Aug. 31, 2000.

FIELD OF THE INVENTION

[0002] This invention relates to the fabrication of semiconductordevices. More particularly, this invention relates to selectivedeposition of silicon oxide onto silicon substrates.

BACKGROUND OF THE INVENTION

[0003] Optimization of semiconductor fabrication sometimes requires athicker nonconducting film on some components than on other components.Such films of different thicknesses can be made by traditional mask andetch techniques or by selective deposition of the reaction product ofTEOS and ozone.

[0004] Traditional mask and etch methods of forming oxide layers andspacers of different thicknesses requires the application of a firstmask over select parts of the semiconductor device and then depositing alayer of silicon oxide over the unmasked parts of the semiconductordevice. The first mask is then removed and a second mask is applied overthe parts that have been coated with the first silicon oxide layerleaving other parts unmasked. Subsequently, a second silicon oxide layeris deposited on the unmasked parts. Finally, an etch is used to removesilicon oxide from select surfaces, leaving behind an oxide layer orspacers where desired. This process adds a number of steps to themanufacturing procedures thereby increasing the complexity of thefabrication. As such, semiconductors are typically manufactured oxidewith oxide layers or spacers of an intermediate thickness that will workacceptably, although not optimally, for substrates of differentconductivity or composition.

[0005] The selective deposition of TEOS/ozone on silicon in preferenceto silicon nitride has been disclosed in the prior art. Copending U.S.patent application Ser. No. 09/652,188 filed Aug. 31, 2000 disclosesselective deposition of TEOS/ozone wherein the selectivity is based ondifferences in the doping of silicon. In situations where theseselective deposition techniques are usable they provide means to formdifferent thickness oxide layers in one step, thereby saving processtime. The current invention improves upon the selectivity of thesemethods.

[0006] A hallmark of the current invention is the provision of a processthat selectively deposits silicon oxide based on the characteristics ofthe underlying substrate and pulsed delivery of the reactants.

SUMMARY OF THE INVENTION

[0007] The current invention is a method for enhancing selectivedepositing silicon oxide onto a substrate surface, wherein theselectivity is based on the conductivity and/or the composition of thesubstrate, by pulsing the delivery of the reactants.

[0008] One preferred embodiment is a method for selectively depositingsilicon oxide onto a substrate, the method comprising the steps of:providing a substrate having at least one exposed region of silicon andat least one exposed region of silicon nitride and/or comprising atleast one exposed silicon region of one type of conductivity and atleast one exposed silicon region of a different type conductivity;delivering, via a linear injector, ozone and tetraethylorthosilicateinto contact with the substrate and with each other, wherein thedelivery of the ozone is pulsed on and off; and reacting the ozone andtetraethylorthosilicate in contact with the substrate to selectivelydeposit silicon oxide onto the substrate.

[0009] Another preferred embodiment is a method for selectivelydepositing silicon oxide onto a substrate, the method comprising thesteps of: providing a substrate having at least one exposed region ofsilicon and at least one exposed region of silicon nitride and/orcomprising at least one exposed silicon region of one type ofconductivity and at least one exposed silicon region of a different typeconductivity; delivering, via a linear injector, ozone andtetraethylorthosilicate into contact with the substrate and with eachother, wherein the delivery of the ozone is pulsed on and off; andreacting the ozone and tetraethylorthosilicate in contact with thesubstrate to selectively deposit silicon oxide onto the substrate,wherein the reaction occurs at a temperature up to about 500° C. and apressure of at least about 10 torr.

[0010] A further preferred embodiment is a method for selectivelydepositing silicon oxide onto a substrate, the method comprising thesteps of: providing a substrate having at least one exposed region ofsilicon and at least one exposed region of silicon nitride and/orcomprising at least one exposed silicon region of one type ofconductivity and at least one exposed silicon region of a different typeconductivity; delivering, via a linear injector, ozone andtetraethylorthosilicate into contact with the substrate and with eachother, wherein the delivery of the ozone and the delivery of thetetraethylorthosilicate are pulsed on and off alternately; and reactingthe ozone and tetraethylorthosilicate in contact with the substrate toselectively deposit silicon oxide onto the substrate.

[0011] Still another preferred embodiment is a method for selectivelydepositing silicon oxide onto a substrate, the method comprising thesteps of: providing a substrate having at least one exposed region ofsilicon and at least one exposed region of silicon nitride and/orcomprising at least one exposed silicon region of one type ofconductivity and at least one exposed silicon region of a different typeconductivity; delivering, via a linear injector, ozone andtetraethylorthosilicate into contact with the substrate and with eachother, wherein the delivery of the ozone and the delivery of thetetraethylorthosilicate are pulsed on and off alternately; and reactingthe ozone and tetraethylorthosilicate in contact with the substrate toselectively deposit silicon oxide onto the substrate, wherein thereaction occurs at a temperature up to about 500° C. and a pressure ofat least about 10 torr.

[0012] A further preferred embodiment is a semiconductor processingmethod of forming spacers of variable thickness, the method comprisingthe steps of: providing a silicon-comprising substrate having a surfacecomprising at least one first conductive region comprising either P-typesilicon or non-doped silicon and at least one second conductive region,provided that: (1) when the first conductive region comprises P-typesilicon, then the second conductive region comprises either non-dopedsilicon or N-type silicon; and, (2) when the first conductive regioncomprises non-doped silicon, then the second conductive region comprisesN-type silicon; decomposing tetraethylorthosilicate with ozone toselectively deposit silicon oxide over the silicon surface and over boththe first conductive region and the second conductive region, whereindelivery of the ozone is pulsed on and off whereby a greater thicknessof silicon oxide is deposited on the first conductive region than on thesecond conductive region and delivery of the ozone and thetetraethylorthosilicate is via a linear injector; and, etching thesilicon oxide deposited on the substrate to remove silicon oxide fromthe surface of the substrate, whereby the silicon oxide layers remainingon the first and second conductive regions provides a layer of variablethickness around the first conductive region and the second conductiveregion.

[0013] Another preferred embodiment is a semiconductor processing methodof forming spacers of variable thickness, the process comprising thesteps of: providing a silicon-comprising substrate having a surfacecomprising at least one first conductive region comprising either P-typesilicon or non-doped silicon and at least one second conductive region,provided that: (1) when the first conductive region comprises P-typesilicon, then the second conductive region comprises either non-dopedsilicon or N-type silicon; and, (2) when the first conductive regioncomprises non-doped silicon, then the second conductive region comprisesN-type silicon; contacting silicon-comprising substrate with ozone andtetraethylorthosilicate wherein delivery of the ozone is pulsed on andoff whereby the first conductive region and the second conductive regionare in intimate contact with the ozone and the tetraethylorthosilicateand delivery of the ozone and the tetraethylorthosilicate is via alinear injector; reacting the ozone and the tetraethylorthosilicate at atemperature up to about 500° C. and a pressure of at least about 10 torrto selectively deposit silicon oxide over the substrate surface and boththe first conductive region and the second conductive region, whereby agreater thickness of silicon oxide is deposited on the first conductiveregion than on the second conductive region; and, etching the siliconoxide deposited on the substrate to remove silicon oxide from thesurface of the substrate, whereby the silicon oxide layers remaining onthe first and second conductive regions provides a layer of variablethickness around the first conductive region and the second conductiveregion.

[0014] Yet another preferred embodiment is a semiconductor processingmethod of forming spacers of variable thickness, the method comprisingthe steps of: providing a silicon-comprising substrate having a surfacecomprising at least one first protrusion comprising either P-typesilicon or non-doped silicon and at least one second protrusion,provided that: (1) when the first protrusion comprises P-type siliconthen the second protrusion comprises either non-doped silicon or N-typesilicon; and, (2) when the first protrusion comprises non-doped siliconthen the second protrusion comprises N-type silicon; contacting thewafer surface with ozone and tetraethylorthosilicate wherein delivery ofthe ozone is pulsed on and off, and delivery of the ozone and thetetraethylorthosilicate is via a linear injector, whereby the firstprotrusion and the second protrusion are in intimate contact with theozone and the tetraethylorthosilicate; decomposing thetetraethylorthosilicate with the ozone to selectively deposit siliconoxide over the wafer surface and both the first protrusion and thesecond protrusion, whereby a greater thickness of silicon oxide isdeposited on the first protrusion than on the second protrusion; and,etching the silicon oxide deposited on the substrate to remove siliconoxide from the surface of the substrate, whereby the silicon oxidelayers remaining on the first and second protrusions provides a layer ofvariable thickness around the first protrusion and the secondprotrusion.

[0015] Another preferred embodiment is a semiconductor processing methodof forming spacers of variable thickness, the process comprising thesteps of: providing a silicon-comprising substrate having a surfacecomprising at least one first protrusion comprising either P-typesilicon or non-doped silicon and at least one second protrusion,provided that: (1) when the first protrusion comprises P-type silicon,then the second protrusion comprises either non-doped silicon or N-typesilicon; and, (2) when the first protrusion comprises non-doped silicon,then the second protrusion comprises N-type silicon; reacting ozone andTEOS at a temperature up to about 500° C. and a pressure of at leastabout 10 torr wherein delivery of the ozone is pulsed on and off, anddelivery of the ozone and the tetraethylorthosilicate is via a linearinjector, to selectively deposit silicon oxide over the wafer surfaceand both the first protrusion and the second protrusion, whereby agreater thickness of silicon oxide is deposited on the first protrusionthan on the second protrusion; and, etching the silicon oxide depositedon the substrate to remove silicon oxide from the surface of thesubstrate, whereby the silicon oxide layers remaining on the first andsecond protrusions provides a layer of variable thickness around thefirst protrusion and the second protrusion.

[0016] A further preferred embodiment is a semiconductor processingmethod of forming wordlines with spacers of variable thickness, theprocess comprising the steps of: providing a silicon-comprisingsubstrate having a surface comprising at least one first wordlinecomprising P-type silicon and at least one second wordline comprisingN-type silicon: reacting ozone and tetraethylorthosilicate at atemperature up to about 500° C. and a pressure of at least about 10 torrwherein delivery of the ozone is pulsed on and off, and the ozone andthe tetraethylorthosilicate are delivered via a linear injector, toselectively deposit silicon oxide over the wafer surface and both thefirst wordline and the second wordline, whereby a greater thickness ofsilicon oxide is deposited on the first wordline than on the secondwordline; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second wordlinesprovides a layer of variable thickness around the first wordline and thesecond wordline.

[0017] A preferred embodiment is a semiconductor processing method offorming spacers of variable thickness, the method comprising the stepsof: providing a silicon-comprising substrate having a surface comprisingat least one first conductive region comprising either P-type silicon ornon-doped silicon and at least one second conductive region, providedthat: (1) when the first conductive region comprises P-type silicon,then the second conductive region comprises either non-doped silicon orN-type silicon; and, (2) when the first conductive region comprisesnon-doped silicon, then the second conductive region comprises N-typesilicon; decomposing tetraethylorthosilicate with ozone to selectivelydeposit silicon oxide over the silicon surface and over both the firstconductive region and the second conductive region, wherein delivery ofthe ozone and the tetraethylorthosilicate are alternately pulsed on andoff, whereby a greater thickness of silicon oxide is deposited on thefirst conductive region than on the second conductive region anddelivery of the ozone and the tetraethylorthosilicate is via a linearinjector; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second conductiveregions provides a layer of variable thickness around the firstconductive region and the second conductive region.

[0018] Another preferred embodiment is a semiconductor processing methodof forming spacers of variable thickness, the process comprising thesteps of: providing a silicon-comprising substrate having a surfacecomprising at least one first conductive region comprising either P-typesilicon or non-doped silicon and at least one second conductive region,provided that: (1) when the first conductive region comprises P-typesilicon, then the second conductive region comprises either non-dopedsilicon or N-type silicon; and, (2) when the first conductive regioncomprises non-doped silicon, then the second conductive region comprisesN-type silicon; contacting silicon-comprising substrate with ozone andtetraethylorthosilicate wherein the ozone delivery and thetetraethylorthosilicate are alternately pulsed on and off whereby thefirst conductive region and the second conductive region are in intimatecontact with the ozone and the tetraethylorthosilicate and the deliveryof the ozone and the tetraethylorthosilicate is via a linear injector;reacting the ozone and the tetraethylorthosilicate at a temperature upto about 500° C. and a pressure of at least about 10 torr to selectivelydeposit silicon oxide over the substrate surface and both the firstconductive region and the second conductive region, whereby a greaterthickness of silicon oxide is deposited on the first conductive regionthan on the second conductive region; and, etching the silicon oxidedeposited on the substrate to remove silicon oxide from the surface ofthe substrate, whereby the silicon oxide layers remaining on the firstand second conductive regions provides a layer of variable thicknessaround the first conductive region and the second conductive region.

[0019] Still another preferred embodiment is a semiconductor processingmethod of forming spacers of variable thickness, the method comprisingthe steps of: providing a silicon-comprising substrate having a surfacecomprising at least one first protrusion comprising either P-typesilicon or non-doped silicon and at least one second protrusion,provided that: (1) when the first protrusion comprises P-type siliconthen the second protrusion comprises either non-doped silicon or N-typesilicon; and, (2) when the first protrusion comprises non-doped siliconthen the second protrusion comprises N-type silicon; contacting thewafer surface with ozone and tetraethylorthosilicate wherein delivery ofthe ozone and the tetraethylorthosilicate are alternately pulsed on andoff, and the delivery of the ozone and the tetraethylorthosilicate isvia a linear injector, whereby the first protrusion and the secondprotrusion are in intimate contact with the ozone and thetetraethylorthosilicate; decomposing the tetraethylorthosilicate withthe ozone to selectively deposit silicon oxide over the wafer surfaceand both the first protrusion and the second protrusion, whereby agreater thickness of silicon oxide is deposited on the first protrusionthan on the second protrusion; and, etching the silicon oxide depositedon the substrate to remove silicon oxide from the surface of thesubstrate, whereby the silicon oxide layers remaining on the first andsecond protrusions provides a layer of variable thickness around thefirst protrusion and the second protrusion.

[0020] Yet another preferred embodiment is a semiconductor processingmethod of forming spacers of variable thickness, the process comprisingthe steps of: providing a silicon-comprising substrate having a surfacecomprising at least one first protrusion comprising either P-typesilicon or non-doped silicon and at least one second protrusion,provided that: (1) when the first protrusion comprises P-type silicon,then the second protrusion comprises either non-doped silicon or N-typesilicon; and, (2) when the first protrusion comprises non-doped silicon,then the second protrusion comprises N-type silicon; reacting ozone andTEOS at a temperature up to about 500° C. and a pressure of at leastabout 10 torr wherein delivery of the ozone and thetetraethylorthosilicate are alternately pulsed on and off, and deliveryof the ozone and the tetraethylorthosilicate is via a linear injector,to selectively deposit silicon oxide over the wafer surface and both thefirst protrusion and the second protrusion, whereby a greater thicknessof silicon oxide is deposited on the first protrusion than on the secondprotrusion; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second protrusionsprovides a layer of variable thickness around the first protrusion andthe second protrusion.

[0021] Another preferred embodiment is a semiconductor processing methodof forming wordlines with spacers of variable thickness, the processcomprising the steps of: providing a silicon-comprising substrate havinga surface comprising at least one first wordline comprising P-typesilicon and at least one second wordline comprising N-type silicon:reacting ozone and tetraethylorthosilicate at a temperature up to about500° C. and a pressure of at least about 10 torr wherein delivery of theozone and the tetraethylorthosilicate are alternately pulsed on and off,and the ozone and the tetraethylorthosilicate are delivered via a linearinjector, to selectively deposit silicon oxide over the wafer surfaceand both the first wordline and the second wordline, whereby a greaterthickness of silicon oxide is deposited on the first wordline than onthe second wordline; and, etching the silicon oxide deposited on thesubstrate to remove silicon oxide from the surface of the substrate,whereby the silicon oxide layers remaining on the first and secondwordlines provides a layer of variable thickness around the firstwordline and the second wordline.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Preferred embodiments of the invention are described below withreference to the following accompanying drawings, which are forillustrative purposes only. Throughout the following views, referencenumerals will be used in the drawings, and the same reference numeralswill be used throughout the several views and in the description toindicate same or like parts.

[0023]FIG. 1 is a cross-sectional view of a silicon-comprising substratehaving an N-type silicon-comprising protrusion and a P-typesilicon-comprising protrusion.

[0024]FIG. 2 shows the substrate of FIG. 2 following selectivedepositing of silicon oxide.

[0025]FIG. 3 shows the substrate of FIG. 3 following an etch processingstep.

[0026]FIG. 4 shows a schematic drawing of a linear injector usable inthe current inventor.

[0027]FIG. 5 is a bar graph comparing uniformity, selectivity anddeposition rate for a pulsed reactant process.

DETAILED DESCRIPTION

[0028] In the following detailed description, references are made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and thatstructural, logical and electrical changes may be made without departingfrom the spirit and scope of the present invention. single crystalsilicon, epitaxial silicon or polysilicon. Protrusion 21 has a P-typedoped silicon layer 23. Protrusion 22 has an N-type doped silicon layer24. Protrusions 21 and 22 each have a metalized film 25, such astungsten silicide, arrayed atop the doped polysilicon layers 23 and 24,respectively.

[0029] The substrate 20 (single crystal) and protrusions 21 and 22 arecontacted with gaseous ozone and gaseous TEOS under conditions where asilicon oxide layer 30 is deposited over the substrate and protrusionsas shown in FIG. 2. At the proper reaction conditions, the silicon oxidewill deposit selectively onto the substrate and protrusions in a singleprocess step. The selectivity of this single process step avoids thenecessity of masking and performing multiple photolithographic steps toform a suitably thick oxide layer or spacer 30 over the component layersof the protrusions 21, 22 and the substrate 20. As shown a thicker layer26 is formed over the P-type layer 23. An intermediate thickness layer27 is deposited over non-doped silicon substrate 20. A thinner layer 24is deposited over the N-type silicon layer 24. An intermediate thicknesslayer 29 is deposited over metalized silicide film layer 25.

[0030] Appropriate reaction conditions for the selective deposition ofsilicon oxide over materials with different type doping is similar tothe reaction conditions used in conventional methods to obtain selectivedeposition on silicon versus silicon nitride. Such reaction conditionsare known in the art as shown in U.S. Pat. No. 5,665,644, incorporatedherein by reference. Typically, the reaction temperature is greater thanabout 200° C. up to about 500° C., preferably up to about 400° C.Generally, the selectivity of the deposition is more pronounced at lowerreaction temperatures. The reaction pressure is at least about 10 torr,preferably at least about 300 torr up to about atmospheric pressure,more preferably up to about 600 torr.

[0031] An exemplary reaction supplies about five liters per minute ofoxygen containing about 10% by weight ozone and about 350 milligrams perminute TEOS. The oxygen: ozone ratio may photolithographic steps to forma suitably thick oxide layer or spacer 30 over the component layers ofthe protrusions 21, 22 and the substrate 20. As shown a thicker layer 26is formed over the P-type layer 23. An intermediate thickness layer 27is deposited over non-doped silicon substrate 20. A thinner layer 24 isdeposited over the N-type silicon layer 24. An intermediate thicknesslayer 29 is deposited over metalized suicide film layer 25.

[0032] Appropriate reaction conditions for the selective deposition ofsilicon oxide over materials with different type doping is similar tothe reaction conditions used in conventional methods to obtain selectivedeposition on silicon versus silicon nitride. Such reaction conditionsare known in the art as shown in U.S. Pat. No. 5,665,644, incorporatedherein by reference. Typically, the reaction temperature is greater thanabout 200° C. up to about 500° C., preferably up to about 400° C.Generally, the selectivity of the deposition is more pronounced at lowerreaction temperatures. The reaction pressure is at least about 10 torr,preferably at least about 300 torr up to about atmospheric pressure,more preferably up to about 600 torr.

[0033] An exemplary reaction supplies about five liters per minute ofoxygen containing about 10% by weight ozone and about 350 milligrams perminute TEOS. The oxygen:ozone ratio may typically vary from about 2parts oxygen:1 part ozone to about 20 parts oxygen:1 part ozone. Theozone:TEOS ratio typically varies from about 0.5:1 to about 200:1.Reaction times will vary depending on the desired thickness of thedeposited layer, generally about 10-30 seconds.

[0034] Optionally, the surface to receive the oxide layer may be wetcleaned in a dip prior to depositing the oxide layer. A hydrofluoricacid (HF) wet-clean dip provides a marginal enhancement of theselectivity of the deposition. Other wet-clean dips, such as sulfuricacid or non-fluorine type etchants, have not been found to enhance theselectivity of the deposition and may negatively affect the subsequentdeposition.

[0035] Following the deposition of the oxide layer 30, the portion ofthe oxide layer 27 overlying the substrate 20 is selectively etched toexpose the substrate 20, resulting in the structure of FIG. 3 having theoxide layers 26, 28 remaining over the protrusions 21, 22, respectively.Any suitable oxide etching method may be used to remove the oxide layer27 and expose the substrate 20. Preferably, the method provides ananisotropic etch. Suitable etching methods include directional methodssuch as reactive ion etching (RIE). An exemplary etching process is byRIE using a mixture of carbon tetrafluoride (CF₄) at a flow of about 15standard cubic centimeters per minute (sccm), and methylene trifluoride(CHF₃) at 25 sccm for thirty seconds at about 200 millitorr and a powerof 100 watts.

[0036] In one preferred embodiment, the protrusions 21, 22 of FIG. 1represent wordlines of different conductivity. In this embodiment, layer23 represents a wordline comprising P-doped silicon and layer 24represents a wordline comprising N-doped silicon. These wordlines can beincorporated into a memory unit, such as a dynamic random access memory(DRAM), by any suitable means known in the art.

[0037] In another preferred embodiment of the invention, the protrusions21, 22 represent a dual gate structure. In this embodiment, layer 23 inFIG. 1 represents a gate comprising P-doped silicon and layer 24represents a gate comprising N-doped polysilicon.

[0038] The inventors have now found that the selectivity of thedeposition process described above can be enhanced by pulsing thedelivery of the reactants. Appropriate reaction conditions for thepulsed selective deposition of silicon oxide are similar to thenon-pulsed methods to obtain selective deposition as discussed above inreference to FIGS. 1-3. Such reaction conditions are known in the art asshown in U.S. Pat. No. 5,665,644, incorporated herein by reference.Typically, the reaction temperature is greater than about 200° C. up toabout 500° C., preferably up to about 400° C. Generally, the selectivityof the deposition is more pronounced at lower reaction temperatures. Thereaction pressure is at least about 10 torr, preferably at least about300 torr up to about atmospheric pressure, more preferably up to about600 torr.

[0039] An exemplary reaction supplies at least the following twoingredients: (i) about five liters per minute of oxygen containing about10% by weight ozone; and, (ii) about 350 milligrams per minute TEOS. Theoxygen:ozone ratio may typically vary from about 2 parts oxygen:1 partozone to about 20 parts oxygen:1 part ozone. The ozone: TEOS ratiotypically varies from about 0.5:1 to about 200:1. Reaction times willvary depending on the desired thickness of the deposited layer,generally about 10-30 seconds.

[0040] In a preferred embodiment wherein the TEOS delivery rate is heldconstant, the ozone delivery is be pulsed on and off with a pulseduration of about 1 to about 4 seconds, preferably about 1 second.

[0041] In another preferred embodiment the TEOS and the ozone deliveryrates are both alternately pulsed on and off for a pulse duration ofabout 1 to about 4 seconds, preferably about 2 seconds.

[0042] The delivery of the gases may be pulsed by any suitable means ofstarting and stopping flow. Such means are well known in the art and caninclude, inter alia, solenoid valves. Although the reactant gases may bedelivered via any suitable injector, a linear injector is preferred overa showerhead injector on the basis of superior uniformity of the oxidelayer thickness. Linear injectors and showerhead injectors are known inthe art. An example of a linear injector suitable for use in thisinvention is disclosed in U.S. Pat. No. 5,855,957 which is incorporatedherein by reference. An example of a typical showerhead injector isdisclosed in U.S. Pat. No. 6,050,506 which is incorporated herein byreference.

[0043] A linear injection system usable for this invention is shownschematically in FIG. 4. The injector 214 generally includes a centralinjection port 220, two outer injection ports 222, and separation ports224 positioned between the central ports 220 and each of the outer ports222. In accordance with this invention, the central injection port 220is coupled to an ozone source 226, the outer ports 222 are coupled to achemical reagent source 228, and the separation ports 224 are coupled toa source 230 of an inert gas such as nitrogen to prevent prematuremixing of the reagent and ozone which could lead to powder formation.The chemical reagent is tetraethoxysilane (TEOS). In the illustratedembodiment, the TEOS vapor is delivered to the outer ports 222 from abubbler at 65.degree. C. by nitrogen carrier gas. However, other meansmay be used to deliver the chemical reagent to the outer ports 222 as isknown in the art.

[0044] Ozone may be injected through the central port 220 at a flow rateof about 2 to 10 standard liter per minute (slm). The ozone ispreferably supplied in a mixture of ozone and oxygen having an ozoneconcentration of about 70 to 150 g/m.sup.3 ozone. The chemical reagentor TEOS can be supplied at a flow rate of 10 to 50 standard cubiccentimeters per minute (sccm), and injected through the outer ports witha Nitrogen carrier gas at a flow rate of about 0.5 to 8 slm. The ratioof ozone to TEOS introduced into the chamber is in the range of 10:1 to30:1. The injected gases mix and react to deposit a film on the surfaceof the wafer.

[0045] Examples of the enhanced selectivity obtained by the currentinvention are shown in FIG. 5 for substrates of silicon and SiN. FIG. 5shows the selectivity, standard deviation and deposition rate forvarious pulsing options and film thickness. Selectivity is the preferreddeposition on silicon versus SiN and is defined as:

Selectivity=(T _(Si) /T _(SiN)−1)×100%,

[0046] where T_(Si) is the oxide film thickness deposited onto a siliconsubstrate and T_(SiN) is the oxide film thickness deposited onto a SiNsubstrate.

[0047] The examples shown in FIG. 5 were produced using a showerheaddesign injector to deliver 350 milligrams per minute TEOS and about fiveliters per minute of oxygen containing about 10% by weight ozone.Pulsing was done at 1 second intervals for pulsed TEOS delivery andpulsed ozone delivery. Pulsing was done at 2 second intervals foralternating TEOS and ozone delivery. The reaction temperature was about400° C. The reaction pressure was about 500 torr. The reaction timeswere varied as necessary to obtain the desired thickness of thedeposited layer, but were generally about 10-30 seconds. The spacingbetween the showerhead and the substrate was 150 mil for the standardno-pulse, Examples (Ex.) A and C, and Comparative Sample (C.S.) 1. Thespacing between the showerhead and the substrate was 200 mil for ExampleB and C.S. 2.

[0048] As shown in FIG. 5, pulsing the delivery of ozone (Ex. A)improved the selectivity of oxide deposition by 28% over the standardno-pulse conditions (50% selectivity vs. 35% selectivity, respectively).Cross wafer uniformity suffers in this regime using a showerhead gasdispersion system. However, the cross wafer uniformity would not be anissue when using a linear injector due to the ability of a linearinjector to distribute the reactant gases uniformly. The selectivityeffect is muted at higher film thickness, as should be expected becausethe substrate is effectively masked from the reactants as the oxidelayer builds up. Comparing Ex. A and Ex. B, the selectivity and standarddeviation are better with a tighter showerhead/substrate spacing.Alternating, mutually exclusive pulses of TEOS and ozone (Ex. C) resultin a much lower deposition rate but an at least 14% higher selectivitycompared to the no pulse process (43% vs. 35%, respectively). Again, thealternating pulses result in a decrease in cross wafer uniformity butuse of a linear injector is expected to provide acceptable uniformity.

[0049] C.S. 1 and C.S. 2 demonstrate that both selectivity anduniformity are worse than standard no pulse conditions when only theTEOS is pulsed.

[0050] The methods and devices of the current invention are usefulwhenever semiconductors are fabricated with silicon-comprising regionsor structures having different type conductivities. Examples of usefulapplications include memory arrays, such as DRAM and static randomaccess memory (SRAM), logic circuitry, and combinations of memory andlogic, such as a system-on-chip array.

[0051] In compliance with the statute, the invention has been describedin language more or less specific as to structural and methodicalfeatures. It is to be understood, however, that the invention is notlimited to the specific features shown and described, since the meansherein disclosed comprise preferred forms of putting the invention intoeffect. The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A method for selectively depositing silicon oxideonto a substrate, the method comprising the steps of: providing asubstrate having at least one exposed region of silicon and at least oneexposed region of silicon nitride and/or comprising at least one exposedsilicon region of one type of conductivity and at least one exposedsilicon region of a different type conductivity; delivering, via alinear injector, ozone and tetraethylorthosilicate into contact with thesubstrate and with each other, wherein the delivery of the ozone ispulsed on and off; and reacting the ozone and tetraethylorthosilicate incontact with the substrate to selectively deposit silicon oxide onto thesubstrate.
 2. Method of claim 1 wherein the ozone is pulsed for 1-4second intervals.
 3. Method of claim 1 wherein the ozone is pulsed for 1second intervals.
 4. A method for selectively depositing silicon oxideonto a substrate, the method comprising the steps of: providing asubstrate having at least one exposed region of silicon and at least oneexposed region of silicon nitride and/or comprising at least one exposedsilicon region of one type of conductivity and at least one exposedsilicon region of a different type conductivity; delivering, via alinear injector, ozone and tetraethylorthosilicate into contact with thesubstrate and with each other, wherein the delivery of the ozone ispulsed on and off; and reacting the ozone and tetraethylorthosilicate incontact with the substrate to selectively deposit silicon oxide onto thesubstrate, wherein the reaction occurs at a temperature up to about 500°C. and a pressure of at least about 10 torr.
 5. The method of claim 4,wherein the reaction occurs at a temperature up to about 400° C.
 6. Themethod of claim 4, wherein the reaction occurs at a pressure of at leastabout 300 torr.
 7. The method of claim 4 wherein the ozone is pulsed atintervals between 1-4 seconds.
 8. The method of claim 4 wherein theozone is pulsed at intervals of about 1 second.
 9. A method forselectively depositing silicon oxide onto a substrate, the methodcomprising the steps of: providing a substrate having at least oneexposed region of silicon and at least one exposed region of siliconnitride and/or comprising at least one exposed silicon region of onetype of conductivity and at least one exposed silicon region of adifferent type conductivity; delivering, via a linear injector, ozoneand tetraethylorthosilicate into contact with the substrate and witheach other, wherein the delivery of the ozone and the delivery of thetetraethylorthosilicate are pulsed on and off alternately; and reactingthe ozone and tetraethylorthosilicate in contact with the substrate toselectively deposit silicon oxide onto the substrate.
 10. The method ofclaim 9 wherein the alternate pulse durations are between about 1 toabout 4 seconds.
 11. The method of claim 9 wherein the alternate pulsedurations are about 2 seconds.
 12. A method for selectively depositingsilicon oxide onto a substrate, the method comprising the steps of:providing a substrate having at least one exposed region of silicon andat least one exposed region of silicon nitride and/or comprising atleast one exposed silicon region of one type of conductivity and atleast one exposed silicon region of a different type conductivity;delivering, via a linear injector, ozone and tetraethylorthosilicateinto contact with the substrate and with each other, wherein thedelivery of the ozone and the delivery of the tetraethylorthosilicateare pulsed on and off alternately; and reacting the ozone andtetraethylorthosilicate in contact with the substrate to selectivelydeposit silicon oxide onto the substrate, wherein the reaction occurs ata temperature up to about 500° C. and a pressure of at least about 10torr.
 13. The method of claim 12 wherein the reaction occurs at atemperature up to about 400° C.
 14. The method of claim 12 wherein thereaction occurs at a pressure of at least about 300 torr.
 15. The methodof claim 12 wherein the alternate pulse duration is between about 1 toabout 4 seconds.
 16. The method of claim 12 wherein the alternate pulseduration is about 2 seconds.
 17. A semiconductor processing method offorming spacers of variable thickness, the method comprising the stepsof: providing a silicon-comprising substrate having a surface comprisingat least one first conductive region comprising either P-type silicon ornon-doped silicon and at least one second conductive region, providedthat: (1) when the first conductive region comprises P-type silicon,then the second conductive region comprises either non-doped silicon orN-type silicon; and, (2) when the first conductive region comprisesnon-doped silicon, then the second conductive region comprises N-typesilicon; decomposing tetraethylorthosilicate with ozone to selectivelydeposit silicon oxide over the silicon surface and over both the firstconductive region and the second conductive region, wherein delivery ofthe ozone is pulsed on and off whereby a greater thickness of siliconoxide is deposited on the first conductive region than on the secondconductive region and delivery of the ozone and thetetraethylorthosilicate is via a linear injector; and, etching thesilicon oxide deposited on the substrate to remove silicon oxide fromthe surface of the substrate, whereby the silicon oxide layers remainingon the first and second conductive regions provides a layer of variablethickness around the first conductive region and the second conductiveregion.
 18. The method of claim 17 wherein the pulse duration is betweenabout 1 to about 4 seconds.
 19. The method of claim 17 wherein the pulseduration is about 1 second.
 20. A semiconductor processing method offorming spacers of variable thickness, the process comprising the stepsof: providing a silicon-comprising substrate having a surface comprisingat least one first conductive region comprising either P-type silicon ornon-doped silicon and at least one second conductive region, providedthat: (1) when the first conductive region comprises P-type silicon,then the second conductive region comprises either non-doped silicon orN-type silicon; and, (2) when the first conductive region comprisesnon-doped silicon, then the second conductive region comprises N-typesilicon; contacting silicon-comprising substrate with ozone andtetraethylorthosilicate wherein delivery of the ozone is pulsed on andoff whereby the first conductive region and the second conductive regionare in intimate contact with the ozone and the tetraethylorthosilicateand delivery of the ozone and the tetraethylorthosilicate is via alinear injector; reacting the ozone and the tetraethylorthosilicate at atemperature up to about 500° C. and a pressure of at least about 10 torrto selectively deposit silicon oxide over the substrate surface and boththe first conductive region and the second conductive region, whereby agreater thickness of silicon oxide is deposited on the first conductiveregion than on the second conductive region; and, etching the siliconoxide deposited on the substrate to remove silicon oxide from thesurface of the substrate, whereby the silicon oxide layers remaining onthe first and second conductive regions provides a layer of variablethickness around the first conductive region and the second conductiveregion.
 21. The method of claim 20 wherein the reaction occurs at atemperature up to about 400° C.
 22. The method of claim 20 wherein thereaction occurs at a pressure of at least about 300 torr.
 23. The methodof claim 20 wherein the pulse duration is between 1-4 seconds.
 24. Themethod of claim 20 wherein the pulse duration is about 1 second.
 25. Asemiconductor processing method of forming spacers of variablethickness, the method comprising the steps of: providing asilicon-comprising substrate having a surface comprising at least onefirst protrusion comprising either P-type silicon or non-doped siliconand at least one second protrusion, provided that: (1) when the firstprotrusion comprises P-type silicon then the second protrusion compriseseither non-doped silicon or N-type silicon; and, (2) when the firstprotrusion comprises non-doped silicon then the second protrusioncomprises N-type silicon; contacting the wafer surface with ozone andtetraethylorthosilicate wherein delivery of the ozone is pulsed on andoff, and delivery of the ozone and the tetraethylorthosilicate is via alinear injector, whereby the first protrusion and the second protrusionare in intimate contact with the ozone and the tetraethylorthosilicate;decomposing the tetraethylorthosilicate with the ozone to selectivelydeposit silicon oxide over the wafer surface and both the firstprotrusion and the second protrusion, whereby a greater thickness ofsilicon oxide is deposited on the first protrusion than on the secondprotrusion; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second protrusionsprovides a layer of variable thickness around the first protrusion andthe second protrusion.
 26. A semiconductor processing method of formingspacers of variable thickness, the process comprising the steps of:providing a silicon-comprising substrate having a surface comprising atleast one first protrusion comprising either P-type silicon or non-dopedsilicon and at least one second protrusion, provided that: (1) when thefirst protrusion comprises P-type silicon, then the second protrusioncomprises either non-doped silicon or N-type silicon; and, (2) when thefirst protrusion comprises non-doped silicon, then the second protrusioncomprises N-type silicon; reacting ozone and TEOS at a temperature up toabout 500° C. and a pressure of at least about 10 torr wherein deliveryof the ozone is pulsed on and off, and delivery of the ozone and thetetraethylorthosilicate is via a linear injector, to selectively depositsilicon oxide over the wafer surface and both the first protrusion andthe second protrusion, whereby a greater thickness of silicon oxide isdeposited on the first protrusion than on the second protrusion; and,etching the silicon oxide deposited on the substrate to remove siliconoxide from the surface of the substrate, whereby the silicon oxidelayers remaining on the first and second protrusions provides a layer ofvariable thickness around the first protrusion and the secondprotrusion.
 27. The method of claim 26 wherein the reaction occurs at atemperature up to about 400° C.
 28. The method of claim 26 wherein thereaction occurs at a pressure of at least about 300 torr.
 29. The methodof claim 26 wherein the pulse duration is between 1-4 seconds.
 30. Themethod of claim 26 wherein the pulse duration is about 1 second.
 31. Asemiconductor processing method of forming wordlines with spacers ofvariable thickness, the process comprising the steps of: providing asilicon comprising substrate having a surface comprising at least onefirst wordline comprising P-type silicon and at least one secondwordline comprising N-type silicon, the first and second wordlines beingseparated on the substrate; contacting the substrate with ozone andtetraethylorthosilicate wherein delivery of the ozone is pulsed on andoff, and delivery of the ozone and the tetraethylorthosilicate is via alinear injector, whereby the first wordline and the second wordline arein intimate contact with the ozone and the tetraethylorthosilicate;reacting the ozone and the tetraethylorthosilicate to selectivelydeposit silicon oxide over the substrate surface and both the firstwordline and the second wordline, whereby a greater thickness of siliconoxide is deposited on the first wordline than on the second wordline;and, etching the silicon oxide deposited on the substrate to removesilicon oxide from the surface of the substrate, whereby the siliconoxide layers remaining on the first and second wordlines provides alayer of variable thickness around the first wordline and the secondwordline.
 32. A semiconductor processing method of forming wordlineswith spacers of variable thickness, the process comprising the steps of:providing a silicon-comprising substrate having a surface comprising atleast one first wordline comprising P-type silicon and at least onesecond wordline comprising N-type silicon: reacting ozone andtetraethylorthosilicate at a temperature up to about 500° C. and apressure of at least about 10 torr wherein delivery of the ozone ispulsed on and off, and the ozone and the tetraethylorthosilicate aredelivered via a linear injector, to selectively deposit silicon oxideover the wafer surface and both the first wordline and the secondwordline, whereby a greater thickness of silicon oxide is deposited onthe first wordline than on the second wordline; and, etching the siliconoxide deposited on the substrate to remove silicon oxide from thesurface of the substrate, whereby the silicon oxide layers remaining onthe first and second wordlines provides a layer of variable thicknessaround the first wordline and the second wordline.
 33. The method ofclaim 32 wherein the reaction occurs at a temperature up to about 400°C.
 34. The method of claim 32 wherein the reaction occurs at a pressureof at least about 300 torr.
 35. The method of claim 32 wherein the ozoneis pulsed at intervals between 1-4 seconds.
 36. The method of claim 32wherein the ozone is pulsed at intervals of about 1 second.
 37. Asemiconductor processing method of forming spacers of variablethickness, the method comprising the steps of: providing asilicon-comprising substrate having a surface comprising at least onefirst conductive region comprising either P-type silicon or non-dopedsilicon and at least one second conductive region, provided that: (1)when the first conductive region comprises P-type silicon, then thesecond conductive region comprises either non-doped silicon or N-typesilicon; and, (2) when the first conductive region comprises non-dopedsilicon, then the second conductive region comprises N-type silicon;decomposing tetraethylorthosilicate with ozone to selectively depositsilicon oxide over the silicon surface and over both the firstconductive region and the second conductive region, wherein delivery ofthe ozone and the tetraethylorthosilicate are alternately pulsed on andoff, whereby a greater thickness of silicon oxide is deposited on thefirst conductive region than on the second conductive region anddelivery of the ozone and the tetraethylorthosilicate is via a linearinjector; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second conductiveregions provides a layer of variable thickness around the firstconductive region and the second conductive region.
 38. The method ofclaim 37 wherein the pulse duration is between about 1 to about 4seconds.
 39. The method of claim 37 wherein the pulse duration is about2 seconds.
 40. A semiconductor processing method of forming spacers ofvariable thickness, the process comprising the steps of: providing asilicon-comprising substrate having a surface comprising at least onefirst conductive region comprising either P-type silicon or non-dopedsilicon and at least one second conductive region, provided that: (1)when the first conductive region comprises P-type silicon, then thesecond conductive region comprises either non-doped silicon or N-typesilicon; and, (2) when the first conductive region comprises non-dopedsilicon, then the second conductive region comprises N-type silicon;contacting silicon-comprising substrate with ozone andtetraethylorthosilicate wherein the ozone delivery and thetetraethylorthosilicate are alternately pulsed on and off whereby thefirst conductive region and the second conductive region are in intimatecontact with the ozone and the tetraethylorthosilicate and the deliveryof the ozone and the tetraethylorthosilicate is via a linear injector;reacting the ozone and the tetraethylorthosilicate at a temperature upto about 500° C. and a pressure of at least about 10 torr to selectivelydeposit silicon oxide over the substrate surface and both the firstconductive region and the second conductive region, whereby a greaterthickness of silicon oxide is deposited on the first conductive regionthan on the second conductive region; and, etching the silicon oxidedeposited on the substrate to remove silicon oxide from the surface ofthe substrate, whereby the silicon oxide layers remaining on the firstand second conductive regions provides a layer of variable thicknessaround the first conductive region and the second conductive region. 41.The method of claim 40 wherein the reaction occurs at a temperature upto about 400° C.
 42. The method of claim 40 wherein the reaction occursat a pressure of at least about 300 torr.
 43. The method of claim 40wherein the pulse duration is between 1-4 seconds.
 44. The method ofclaim 40 wherein the pulse duration is about 2 seconds.
 45. Asemiconductor processing method of forming spacers of variablethickness, the method comprising the steps of: providing asilicon-comprising substrate having a surface comprising at least onefirst protrusion comprising either P-type silicon or non-doped siliconand at least one second protrusion, provided that: (1) when the firstprotrusion comprises P-type silicon then the second protrusion compriseseither non-doped silicon or N-type silicon; and, (2) when the firstprotrusion comprises non-doped silicon then the second protrusioncomprises N-type silicon; contacting the wafer surface with ozone andtetraethylorthosilicate wherein delivery of the ozone and thetetraethylorthosilicate are alternately pulsed on and off, and thedelivery of the ozone and the tetraethylorthosilicate is via a linearinjector, whereby the first protrusion and the second protrusion are inintimate contact with the ozone and the tetraethylorthosilicate;decomposing the tetraethylorthosilicate with the ozone to selectivelydeposit silicon oxide over the wafer surface and both the firstprotrusion and the second protrusion, whereby a greater thickness ofsilicon oxide is deposited on the first protrusion than on the secondprotrusion; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second protrusionsprovides a layer of variable thickness around the first protrusion andthe second protrusion.
 46. A semiconductor processing method of formingspacers of variable thickness, the process comprising the steps of:providing a silicon-comprising substrate having a surface comprising atleast one first protrusion comprising either P-type silicon or non-dopedsilicon and at least one second protrusion, provided that: (1) when thefirst protrusion comprises P-type silicon, then the second protrusioncomprises either non-doped silicon or N-type silicon; and, (2) when thefirst protrusion comprises non-doped silicon, then the second protrusioncomprises N-type silicon; reacting ozone and TEOS at a temperature up toabout 500° C. and a pressure of at least about 10 torr wherein deliveryof the ozone and the tetraethylorthosilicate are alternately pulsed onand off, and delivery of the ozone and the tetraethylorthosilicate isvia a linear injector, to selectively deposit silicon oxide over thewafer surface and both the first protrusion and the second protrusion,whereby a greater thickness of silicon oxide is deposited on the firstprotrusion than on the second protrusion; and, etching the silicon oxidedeposited on the substrate to remove silicon oxide from the surface ofthe substrate, whereby the silicon oxide layers remaining on the firstand second protrusions provides a layer of variable thickness around thefirst protrusion and the second protrusion.
 47. The method of claim 46wherein the reaction occurs at a temperature up to about 400° C.
 48. Themethod of claim 46 wherein the reaction occurs at a pressure of at leastabout 300 torr.
 49. The method of claim 46 wherein the pulse duration isbetween 1-4 seconds.
 50. The method of claim 46 wherein the pulseduration is about 2 seconds.
 51. A semiconductor processing method offorming wordlines with spacers of variable thickness, the processcomprising the steps of: providing a silicon comprising substrate havinga surface comprising at least one first wordline comprising P-typesilicon and at least one second wordline comprising N-type silicon, thefirst and second wordlines being separated on the substrate; contactingthe substrate with ozone and tetraethylorthosilicate wherein delivery ofthe ozone and the tetraethylorthosilicate are alternately pulsed on andoff, and delivery of the ozone and the tetraethylorthosilicate is via alinear injector, whereby the first wordline and the second wordline arein intimate contact with the ozone and the tetraethylorthosilicate;reacting the ozone and the tetraethylorthosilicate to selectivelydeposit silicon oxide over the substrate surface and both the firstwordline and the second wordline, whereby a greater thickness of siliconoxide is deposited on the first wordline than on the second wordline;and, etching the silicon oxide deposited on the substrate to removesilicon oxide from the surface of the substrate, whereby the siliconoxide layers remaining on the first and second wordlines provides alayer of variable thickness around the first wordline and the secondwordline.
 52. A semiconductor processing method of forming wordlineswith spacers of variable thickness, the process comprising the steps of:providing a silicon-comprising substrate having a surface comprising atleast one first wordline comprising P-type silicon and at least onesecond wordline comprising N-type silicon: reacting ozone andtetraethylorthosilicate at a temperature up to about 500° C. and apressure of at least about 10 torr wherein delivery of the ozone and thetetraethylorthosilicate are alternately pulsed on and off, and the ozoneand the tetraethylorthosilicate are delivered via a linear injector, toselectively deposit silicon oxide over the wafer surface and both thefirst wordline and the second wordline, whereby a greater thickness ofsilicon oxide is deposited on the first wordline than on the secondwordline; and, etching the silicon oxide deposited on the substrate toremove silicon oxide from the surface of the substrate, whereby thesilicon oxide layers remaining on the first and second wordlinesprovides a layer of variable thickness around the first wordline and thesecond wordline.
 53. The method of claim 52 wherein the reaction occursat a temperature up to about 400° C.
 54. The method of claim 52 whereinthe reaction occurs at a pressure of at least about 300 torr.
 55. Themethod of claim 52 wherein the ozone is pulsed at intervals between 1-4seconds.
 56. The method of claim 52 wherein the ozone is pulsed atintervals of about 2 seconds.